Well, I've only watched a few episodes of Naruto and none of Bleach, but I've been reading both quite thoroughly. Each has its pros and cons, but like Steve said, they're quite different aside from the fighting/action elements, and even in that, they're unique, so it's hard to compare em.
I like how Naruto builds up this whole new world with laws and a history and everything's backed up properly one way or another. Admittedly, I didn't really like it until Shippuuden kicked off, but I like how more of back story involving the Akatsuki is being covered.
Bleach on the other hand, seems to have a more mature 'sense' about it, which I appreciate and it just seems to be more serious to me than Naruto. The only thing I don't like about it is the constant 'powering up when down' thing some of the characters go through, like in DBZ, where out of nowhere they'll pull out some super duper skill or ability in the last second to kill off whoever. It's kinda cliche. :C
Still, I prefer Bleach, no doubt about it. Naruto has a lot of unique characters though, which I like, but other than that, not much.
